Typewriter lift mechanism



April 20, 1954 w. c. MGMAHAN TYPEWRITER LIFT MECHANISM Filed Feb. 24,1951 2 Sheets-Sheet 1 INVENTOR.

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April 20, 1954 w. c. MGMAHAN TYPEWRITER LIFT MECHANISM '2 Sheets-Sheet 2Filed Feb. 24,v 1951 INVENTOR.

T TOE/VE ym, Hh 1%? I u Mc .m M A C. .w mm. Non Nw.. m R m. MM: c I u WW W @Y NN ,mh QN QM. .N .WI uw Sm? n. www. @is w1. m m Nm. Q mw A mm. SwQQ Ww A :wwe m, w NN Sw mm www fm N R .ww wl- Patented Apr. 20, 1954UNITED STATES ATENT OFFICE This invention relates to typewriter liftmechanisms especially adapted to be incorporated in desks.

Such lifts commonly employ a shelf that may he manually moved from aninactive position below the desk top to an active position projectingoutwardly of the desk, and at a convenient height.

Various means, such as springs, may be used in such mechanisms, andwhich partly compensate for the weight of the typewriter supported onthe shelf, to facilitate the manual lifting and lowering of the shelf.

It is one of the objects of this invention to provide a simplifiedmechanism ci this character, and particularly one in which the manualoperation of raising and lowering the typewriter support or shelf isfacilitated.

It is another object of this invention to provide a support which, whenelevated, is positively restrained against inadvertent lowering orsidewise tilting of the shelf.

It is another object of this invention to provide a typewriter supportthat is rigid and that will not vibrate while the operator uses thetypen writer.

This invention possesses many other advantages, and has other objectswhich may be made more clearly apparent from a consideration ci oneembodiment of the invention.

For this purpose, there is shown a form in the drawings accompanying andforming part ci the present specification. The form will now bedescribed in detail, illustrating the general principles of theinvention; but it is to he understood that this detailed description isnot to be taken in a limiting sense, since the scope of this Ainventionis best defined by the appended claims.

Referring to the drawings:

Figure 1 is a vertical section of a typewriter desk incorporating theinvention, the typewriter support being in lowered position;

Fig. 2 is a fragmentary sectional view, taken along a planecorresponding to line 2 2. of Fig. l;

Fig. 3 is a view similar to Fig. 1, but illustrating the typewritersupport in extended or raised position;

Fig. 4 is an enlarged sectional view, taken along a plane correspondingto line -d. of Fig. 3; and

Fig. 5 is an enlarged sectional view, showing the latch-releasingmechanism used in connection with the invention. l Y

A typewriter desk is shown having a top i, a back wall 2, wallsy 3, andlegsv ft.

4 Claims. (Cl. S12- 27) To provide a space 5t for a typewriter at theright-hand side of the desk, a vertical partition 5 (Figs. 2 and 4)extends between a lower desk brace E and the top i.

A shelf-like support l is adapted to be disposed in the lowered positionbeneath the top l, as indicated in Figs. l and 2, or to extend fornwardly to a position near the top of the desk l, illustrated in Figs. 3and 4. In Fig. 3, a typewriter 26 is shown as resting on support 7.

In order to suspend the support l in space 5t, use is made of fourlinks, two at each edge of the support 7. Thus, links 8 and 9, shown inFig. 1, are pivoted at their lower ends to one edge of the support Attheir upper ends these links are pvoted by pivots 22 and 23 on asupporting cleat I0 that is attached to a clearJ il fastened to thepartition 5. A similar supporting cleat I2 (Fig. 2) is attached to acleat l 3 that is placed at the top of the inner side of the wall 3.From this support i3 there extend two links 8 andL il,

similarly arranged to the links shown in Fig. 1.

In the lowered position of Figs. l and 2 the cleats I0 and i2 are injuxtaposed relationship with respect to the support 1. The links 8 and Qare movable to a substantially coincident relations ship with respect tothe cleats it and l2, thereby swinging the support 'l out o1" juxtaposedrelationship with respect to the cleats l@ and i2 and the top l, asillustrated in Fig. 3.

In the loweredposition of Fig. 1, the support l is held againstinadvertent forward movement. as by the aid oi a spring catch Ulfastened to the lower side of the support l, and adapted to engage adetent I5. This detent l5 is supported near the lower edge of thetypewriter opening 5t. The catch it may be released from the detent l5by manually raising this spring latch by the aid of the horizontal endl. When the support 'i is lowered, the catch I4 rides over the detent I5until the parts reach the position of Fig. 1, when the catch snaps intolatching position.

A pair of tension springs Il and It is provided Yfor urging the support'i to the lowered position of Fig. l `or to the raised position of Fig.3. When the support kl' is in the lowered position, the springs exert aforce urging the links 8 and il in a counterclockwise direction, therebymain taining Vthe support .7 in the lowered position. When the latch iaiis released and the support brought forward yto a deiinite point, thesprings Ail and I8 then exert a force vassisting the raising operation.j A g Thus, the left-hand ends of the springs il and i8 are anchored onacross bar i9 extending across the top of the typewriter space 50 andattached to the supports I and I2. The righthand ends of springs I1 andI8 are engaged in apertures formed in an anchor member 2D. This anchormember 2E has legs attached to links 9 (Fig. 2), as by the aid of therivets 2|, In the lowered position of Fig. l, the force of the'springsI1 and I8 on links 9 is directed to the left, and above, the pivots 22,23 of the links 8 and 9. Accordingly, the force of the spring urges thelinks 8 and 9 in a direction to maintain the support 'i in the loweredposition.

Now, when support 1 is moved forwardly, the anchor 20 moves downwardlyand below the pivots 22 and 23. When this downward movement reaches aposition where the direction of the force of the springs is below thesepivots 22 and 23, the force of the springs is in a direction to move thelinks 8 and 9 in a clockwise direction. This clockwise direction is suchas to raise the support 1 ultimately to the position ofsFig. 3. In thisposition, the typewriter 2li is supported at a convenient height foroperation. Similarly, when it is desired to lower the support 1, it maybe urged downwardly and inwardly from the position of Fig. 3 until thesprings i1 and IB assume a position above the pivots 22 and 23.

The space between the opposed supporting bars I3 and I2 is slightly lessthan the width of shelf 's' and links S. These links thus slightlydiverge toward the shelf 1. When theY sheif is raised to the position ofFig. 3, the shelf and links are thus wedged firmly in place, and allvibration is eliminated.

When the support 1' is in the raised position of Fig. 3, it is securelylatched in this position until it is desired to lower the support. Forthis purpose, hooks 25 are disposed on opposite sides of the support 1.These hooks may be formed on the ends of a bent strap 26 that extendsacross the bottom of support 1. These hooks 25 are intended to engage alatch bar 2?. This latch bar extends transversely across the top of thetypewriter opening. It is guided, as by slots 2S located in the ends ofthe supports Iii and I2, and extends beyond these supports (Fig. 4). Theslots 23 extend in a direction parallel to the supports I8 and i2, whichdirection is normal to the direction of movement of the support 's' whenit is in the elevated position of Fig. 3. A pair of tension springs 23is anchored at one end around the bar 21. At the other end, they areanchored on the spring anchor I 9. 29 urge the bar 21 into the slot 33of each of the hooks 25.

The upper surface 3| of each of the hook members 25 is sloping so that,as the hook members are brought up to the position of Fig. 3, thesesloping surfaces engage the bar 21 and urge the bar 21 outwardly of thegroove 23. Then, as the sloping surface SI moves further upwardly, thebar 28 moves inwardly to engage the slots 30. In the engaged positionillustrated in Figs. 3 and 4, the bar 31 is hooked at eachrof itsextremities. Since the support is suspended by hooks at each edge of thesupport, it is eiectively prevented from tilting, as well as frommovingY downwardly, under the weight of the typewriter 24.

In order to release the bar 28 from the hooks 25, use is made of a lever32 pivoted in a clevis 33 mounted on the support 1. rihis lever 32 hasan arm provided with a sloping surface 3d. This sloping surface, whenthe support 1 is in the raised position, underlies the bar 21, as shownThese springs most clearly in Fig. 3. In order to release the bar 21,the lever 32 is moved in a counterclockwise direction, and the slopingsurface 34 engages the bar 21 and moves it to the disengaged position ofFig. 5. In this position, the support 1 may be lowered, as the hooks 25are no longer engaged by the bar 21.

In order to form a limit to the upward movement of the support 1, across member 35 is mounted in front of the clevis 33 on the support i.This cross member is provided with a slot Se to permit the passage ofthe lever 32. Its upper surface closely underlies the upper frameportion 31 of the opening to the typewriter space 53.

The inventor claims:

1. In a lift mechanism: a pair of parallel spaced frame elements havingprovisions for attachment to a cabinet or the like; a mechanism movablycarried by said frame elements and comprising: a support, and aplurality of links pivoted at one end to said support, the other ends ofsome of the links being pivoted to one of said frame elements, the otherends of the other of said links being pivoted tothe other of said frameelements, said links being of equal length between their pivotalmountings for providing a parallelogram suspension for said support;said support being swingable through substantially a quarter revolutionfrom a first position to second position; said frame elements eachhaving at corresponding ends a slot extending in a direction transverseto the direction of movement of said support when said support reachessaid second position; a bar extending between said frame elements andguided by said slots respectively for translation of said bar; a pair ofspring members urging said bar to one position in said slots; and a hookmember rigidly carried by said mechanism and having a cam surfaceengageable with said bar when said support is moved to said secondposition, and also having a latching recess engageable with said barupon continued movement of said support, said recess extendingsubstantiaily parallel to said slots when said support is in said secondposition.

2. In a lift mechanism: a pair of parallel spaced elongate frame membershaving provisions for attachment to a cabinet or the iike; a mechanismmovably carried by said frame members, and comprising: a support, aiirst pair of links each having one end respectively pivoted to one sideof said support and each having another end respectively pivoted to oneof said frame members, and another pair of links each having one endrespectively pivcted to the opposite side of said support and eachhaving another end respectively pivoted to the other oi said framemembers; said linksV all'being of equal length between their pivotalconnections for providing a parallelogram suspension for said support,said support being swingable from a rst juxtaposed position with respectto said frame members to a second position in which said supe port isout of juxtaposed relationship with ren spect to said frame members, thelength of each pair of links respectively between their pivotalconnections being substantially parallel to said frame members when saidSuppenl in said second position; said frame members each having atcorresponding ends a slot extending substantially parallel to thelengthof said frame inembers; a bar extending between said frame members andguided by said slots respectively for translation of said bar; springmeans urging said bar to one position in said slots; a hook memberrigidly carried by said mechanism and having a cam surface engageablewith said bar for moving said bar away from said one position when saidsupport is moved to said second position. said hook member also having alatching recess engageable with said bar upon continued movement of saidsupport, said recess extending substantially parallel to said slots whensaid support is in said second position; and manually operated means formoving said bar away from said one position and out of latchingrelationship with said bar.

3. In a lift mechanism: a pair of parallel spaced frame elements havingprovisions for attachment to a cabinet or the like; a mechanism movablycarried by said frame elements and comprising: a support, and aplurality of links pivoted at one end to said support, the other end ofsome of the links being pivoted to one of said frame elements, the otherends of the other of said links being pivoted to the other of said frameelements, said links being of equal length between their pivotalmountings for providing a parallelogram suspension for said support;said support being swingable through substantially a quarter revolutionfrom a rst position to a second position; a pair of elements rigidlycarried by said mechanism and each having a slot extending in adirection transverse to the direction of movement of said support whensaid support reaches saidv second position; said slots of said elementsof saids mechanism having a substantial length movable into alignmentwith a substantial length of the slots of said frame members when saidmechanism is in said second position; a bar guidingly carried atopposite ends in the slots of one of the pairs of elements; a springexerting a force urging said bar to one position in said one pair ofslots; said bar being movable to another position in said slots of saidone pair of elements against the force of said spring; the slots of theother of said pairs of elements being open to provide a latching recessreceiving said bar when said mechanism is in said second position; saidbar, when said slots are aligned, clearing the open ends of the slots ofsaid other pair of elements when said bar is moved from said oneposition to said other position; and means providing cam surfaces oneach of said other of said pairs of elements adjoining the slotsthereof, and engageable with said bar upon movement of said supporttoward said second position to move said bar to said otherl position.

4. In a lift mechanism: a pair of parallel spaced elements forming aframe member, said elements having provisions for attachment to acabinet or the like; a mechanism movably carried by said frame memberand comprising: a support member, and a plurality of links each pivotedat one end to said support member, and at the other end to said framemember, said links being of equal length between their pivotal mountingsfor providing a parallelogram suspension for said support member; saidsupport member being swingable through substantially a quarterrevolution from a first position to a second position; a latch barextending transversely of the mechanism; means carried by one of themembers for guiding the bar for movement ci translation transverse tothe axes of the link pivots, and transverse to the direction of movementof said support member when said support is in said second position; ahook carried by the other member for engaging the latch bar; said hookhaving a cam surface engageable with said bar when the support member ismoved to said second position, and also having a latching recessengageable with said bar upon continued movement of said support, saidrecess extending in the direction of movement of said bar; and meansresiliently urging said bar into engaging position With respect to saidrecess.

References Cited in the le 0f this patent UNITED STATES PATENTS NumberName Date 883,305 Fetch Mar. 31, 1908 1,137,261 Dyke Apr. 27, 19152,358,917 Emde Sept. 26, 1944 2,561,505 Fox July 24, 1951 FOREIGNPATENTS Number Country Date 162,'103 Switzerland June 15, 1933

